NEW YORK (AP) - Chicago White Sox catcher Welington Castillo was suspended for 80 games by Major League Baseball on Thursday following a positive test for a performance-enhancing substance.

The commissioner's office cited use of EPO. Erythropoietin is a hormone that stimulates the red-blood cell production and often turns up in test results for cyclists.

Castillo apologized in a statement through the players' union, saying he has "let many people down." He pointed to an "extremely poor decision that I, and I alone, made. I take full responsibility for my conduct."

General manager Rick Hahn told reporters on Thursday that he learned of the suspension on Wednesday night as the White Sox pounded Baltimore 11-1.

"Obviously we were surprised, saddened and disappointed to learn of Welington's suspension." Hahn said. "He certainly has stood up and accepted responsibility for his actions. It doesn't change the fact that it's disappointing.

"I've gone through a lot of emotions over the last several hours," he said. "We had ourselves perhaps the most entertaining game of our season (on Wednesday) with a lot of positive things. and quite frankly I didn't really enjoy much of it."

Castillo accepted the penalty without contesting it before arbitrator Mark Irvings. The discipline stemmed from an in-season test, and he became the eighth player suspended this year under the major league drug-testing program.

Castillo is in his ninth major league season. The 31-year-old Dominican is batting .267 with six homers and 15 RBIs this year on a team that is 15-31.

Barring rainouts, he would be eligible to return Aug. 24 at Detroit. He would lose $3,547,043 of his $7.25 million salary, which covers the period of 80 games plus the 11 off-days during that span.

Chicago signed Castillo as a free agent in December 2017 to help guide the team's young pitching staff. Omar Narvaez and Alfredo Gonzalez, who was called up from Triple-A Charlotte on Thursday, will take over behind the plate.

"Obviously it's a little bit of a blow for us, a young man who knows he made a mistake, and I think he'll learn from it," said White Sox manager Rick Renteria, who managed Castillo on the Cubs in 2014. "So we'll make our adjustments, continue to move positively, continue to work, encourage and try to get these guys to just continue to improve.

"There's a disappointment in me. If you want me to use the word angry, I don't have enough time or energy to do that. I think what's done is done. Hopefully everybody learns something from this particular moment, because it's touching us now close to home obviously."

Castillo is due $7.25 million next season, and the White Sox have an $8 million option for 2020 with a $500,000 buyout.

Castillo has a .259 career average with 86 homers and 298 RBIs. He also has played for the Cubs (2010-15), Seattle (2015), Arizona (2015-16) and Baltimore (2017).